Secondary-Prevention Data Strong for Fish Oil Caps: AHA Advisory

Larry Hand

March 17, 2017

NEW YORK, NY — Those with a recent CVD event, such as MI or heart failure without preserved left-ventricular function, may benefit from prescribed omega-3 polyunsaturated fatty acid (PUFA) supplementation, according to a new science advisory from the American Heart Association (AHA)[1].

However, because of a lack of evidence, the advisory does not include recommendations on omega-3 PUFA (fish-oil) supplements for the general population.

"For the general population, there's a lack of evidence regarding the effects of fish-oil supplements in clinical cardiovascular medicine, so for that we don't make a recommendation. We would caution clinicians and patients about claims that are being made with regard to benefit in that population," primary author Dr David S Siscovick (New York Academy of Medicine, NY) told heartwire from Medscape.

The science advisory is an update of an advisory published in 2002[2], which recommended fish oil for patients with documented CHD based on two randomized controlled trials.

For the new advisory, the AHA committee reviewed 11 randomized controlled trials that had major CVD end points and two meta-analyses.

Siscovick explained that the advisory "basically reviews several clinical indications focused on primary or secondary prevention of CVD as well as clinical CV events. We reviewed evidence from large randomized controlled trials. The intent is to make clinicians aware of what's known and what's not known about the use of fish-oil supplements for these indications as it relates to prevention of CVD."

The committee found that omega-3 PUFAs may help reduce CHD deaths by about 10%—possibly by reducing ischemia-induced sudden cardiac death—in patients with prior CHD, as per the 2002 recommendation. They found, however, that supplementation does not lower the incidence of nonfatal MI.

They based their recommendation on results of five randomized controlled trials (two published before 2002 and three since then). The average dose of fish oil in those trials was 1000 mg/day, and the mean duration of the trials was 2 years.

A new finding included in the current advisory is a large trial[3] that showed omega-3 supplementation in patients with chronic heart failure reduced the risk of total mortality by 9% (relative risk [RR] 0.91, 95% CI 0.833–0.998; P=0.041).

Omega-3 supplementation also reduced the risk of CV hospitalization or death by 8% (RR 0.92, 95% CI 0.849–0.999; P=0.009), after adjustment for hospitalization for heart failure during the preceding year, previous pacemaker, and aortic stenosis. Almost all (91%) of the trial patients had heart failure with reduced ejection fraction.

The committee write that no trials have assessed the effect of omega-3 supplementation on the primary prevention of heart failure.

As for primary CHD prevention in the general population—those without prior CHD—they write that there are no randomized controlled trials on the topic and made no recommendation.

The committee also did not make a recommendation on the primary prevention of atrial fibrillation (AF).

They write that no trials of omega-3 supplementation have been about primary prevention of stroke, although stroke was included in composite clinical CVD end points. Trial researchers found supplementation had no benefit in reducing the risk of stroke.

As for secondary stroke prevention, the authors write that no evidence exists of a benefit from omega-3 supplementation in reducing the risk of recurrent stroke or other CVD.

The authors gave a "no benefit recommendation" for the prevention of CVD mortality in those with diabetes and prediabetes, for the secondary prevention of AF in people with prior AF, for the prevention of AF after cardiac surgery, and for the prevention of CHD in people at high risk of CHD and those with no prior clinical CVD.

However, a minority of committee members recommended omega-3 supplementation in people at high risk of CVD because of conflicting evidence.

"We reviewed all the information available from randomized controlled trials with clinical CVD end points," Siscovick told heartwire. "We point out where we think physicians should consider treatment with omega-3 fatty-acid supplements, specifically in the post-MI and heart-failure settings, and other clinical indications for which the evidence to recommend therapy is not as strong."

"We tried to provide enough detail in the advisory so that clinicians could evaluate for themselves the 11 randomized controlled trials that have been available since 2002," he said.

He concluded that "the advisory should help clinicians make sense of the data available from randomized controlled trials. Yet at the same time, it will be of interest to the public and patients."

Siscovick reported no relevant financial relationships. Disclosures for the coauthors are listed in the paper.

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